Antimicrobial thio pyridazine compositions for agricultural use



United States Patent Oiiice 3,089,809 Patented May 14, 1963 3,089 809 ANTIMICROBIAL THHYPYRIDAZEJE COMPC- SITIONS FCR AGRICULTURAL UE .iiro Kinugawa, Osaka, Hiroichi Yamamoto, Kobe, Michipresence of a base such as an alkali metal hydroxide or an alkaline earth metal hydroxide in a solvent such as an alcohol, water, benzene, hexane or a mixture thereof. In the reaction, 3-halo-G-mercaptopyridazine can be rehilro Gchiai, Sarita, and time Surnina Kyoto, Japan, 5 placed with an alkali metal or alkaline earth metal salt assignors to Takeda Pharmaceutical industries, Ltd, thereof, Osaka, Japan '(c) 3-halo-6 thiocyanopyridazine is als 7 0 prepared by fsgllz aw lig E Wf i? allowing the corresponding 3,6-dihalopyridazine to react 2193 3y with an alkali metal or ammonium salt of thiocyanic 11 Claims. (Cl. 167--33) 1O acid in a solvent such as an alcohol, water, an ab- The present invention relates to valuable and novel phatic ketone or a mixture thereof.

TABLE 1 Compound X R M.P. 0.) Appearance Solvent of recrystallization 3-bromo-6-mercaptopyridaziue Br 11 140 145 Yellow powder" Methanol-H O.

3-chloro-6-thiocyanopyridazine. Cl ON 123 124 Colorless powder Eth3nQ1H20, 3-bromo-G-thiocyanopyridazine Br ON 113 115 Yellow powder Acetone-H O. 3-chloro-G-methoxycarbonylthiopyrida. C1 COOCHa 88 -89 Colorless needles Ether-n-hexane. 3-chloro-Gethoxycarbonylthiopyridazinei Cl 000021-15 49.5- 50.5 Colorless prisms n-Hexane. 3-ohloro-6-n-propoxycarbcnylthiopyridazine Cl COO-n-Calfi 61 -62 Yellowish prisms Do. 3 chlorofi-n-butyloxycarbonylthiopyridazine C1 COO-11 C4H9 29 30 Yellowish plates. Do. 3 ohl0ro-G-n-amyloxycarbonylthiopyridazine Cl CQO-D-CsHn 32 33 Do. S-chloro-(i-nhexyloxycarbonylthiopyridazine. Cl COO-n-C H 45 -46 Do. 3-chloro6n-heptyloxycarbonylthiopyridazine Cl COO-ri-C H 45 46 D0. 3-chloro-6-n-octyloxycarbonylthiopyridazine Cl COO-n-C H 59 60 Do. 3-chloro-B-benzyloxycarbonylthiopyrldazine. Cl COOOHz- 101 103 Light yellow needles.- Acetone-n-hexane.

S-chloro-6-phenoxycarbonylthiopyridazine Cl COO-Q 122 -12-t Yellowishneedles Do.

antimicrobial compositions and to their use in agriculture, especially in combating fungi and bacteria which cause, for example, rice blast, rice bacterial leaf blight, cucumber anthracnose, pear black spot, etc., in plants of various kinds.

The antimicrobial compositions of the present invention are characterized by absence of phytotoxicity and by the fact that they contain, as antimicrobial ingredient, at least one compound of the formula wherein X is a halogen, and R is hydrogen, cyano group or OOOR, where R is an alkyl, benzyl or phenyl group.

The compounds :(I) can conveniently be prepared as follows:

(a) 3-halo-6-mercaptopyridazine is preparable after the method reported 'by it. Druey et al. [Helv. Chim. Acta, vol. 37, p. 121 (1954)] and by N. Takabayashi [Journal of the Pharmaceutical Society of Japan, vol. 75, p. 778 (1955)]. Into an organic solvent such as an alcohol or an aliphatic ketone is introduced hydrogen sulfide in the presence of a base such as an alkali metal hydroxide, and to the solution is added 3,6-dihalopyridazine, and then the mixture is refluxed for a few hours, whereupon the corresponding 3-halo-6-mercaptopyridazine is produced.

(b) The compounds (1) except B-halo-G-mercaptopyridazine can be prepared by allowing 3-halo-6-mercaptopyridazine to react with RX, wherein R represents a cyano group, and X represents a halogen atom such as chlorine or bromine, or with ClCOOR, wherein R represents an alkyl, benzyl or phenyl group, in the Examples of the preparation of typical com-pounds of Table 1, which compose the antimicrobial substances of this invention, are shown in the following:

(1) Into a solution of 4.7 parts by weight of potassium hydroxide in 40 parts by volume of methanol is introduced hydrogen sulfide, and then 5 parts by Weight of 3,6-dibromopyridazine is added. The mixture is refluxed for 2 hours on a water-bath. The reaction mixture is concentrated under reduced pressure. To the concentrate is added 35 parts by volume of water. After icecooling, the mixture is filtered, and the filtrate is acidified with 20% hydrochloric acid under ice-cooling to separate out crystals. The crystals are recrystallized from methanol-water to give 3.2 parts by weight of 3-bromo- 6-mercaptopyridazine, which melts at l40-l45 C. with decomposition.

Analysis.Calcd. for C H N BrS: N, 14.66. Found: N, 14.87.

(2) To a solution of 1.2 parts by weight of sodium hydroxide and 4.4 parts by weight of 3-chloro-6-mercaptopyridazine in 30 parts by volume of water is added dropwise a solution of 3.5 parts by weight of cyanogen bromide in 15 parts by volume of ethanol with stirring and ice-cooling at 8 to 10 C. Yellowish crystals precipitate immediately. To the reaction mixture is added 10 parts by volume of water, and the crystals are collected by filtration and recrystallized from ethanol-Water to give 4.8 parts by weight of 3-chloro-6-thiocya'nopyridazine, which melts at 123-l24 C. with decomposition.

Analysis.Calcd. for C H N SCl: C, 34.99; H, 1.17; N, 24.48. Found: C, 35.15; H, 1.13; N, 25.00.

(3) To a solution of 0.3 part by Weight of sodium hydroxide and 1 part by Weight of 3-ch1oro-6-mercaptopyridazine in 10 parts by volume of water is added dropwise a solution of 0.46 part by weight of cyanogen chloride in parts by volume of ethanol under agitation and icecooling. Thereafter the same treatment as in (2.) is applied to the reaction mixture to give 0.8 part by weight of 3-chloro-6-thiocyanopyridazine.

(4) A mixture of parts by weight of 3,6-dichloropyridazine, parts by weight of ammonium thiocyanate and 100 parts by volume of 95% ethanol is warmed at Analysis.-Calcd. for CqH OzN ClSZ C, 38.45; H, 3.22; N, 12.81. Found: C, 38.61; H, 3.35; N, 13.01.

(9) Compounds listed in the following Table 2 are prepared in a similar reaction, but replacing ethyl chlorocarbonate used in (8) with the corresponding chlorocarbonates. Properties of the products, i.e. melting points, appearances and solvents for recrystallization are shown in Table 1.

TABLE 2 Cl -Sfi-OR N=N O C H N R Yield 1 Formula Calcd. Found Calcd. Found Calcd. Found CH5 81 C H O2NzClS 35. 21 35. 2. 4G 2. 42 13.60 13.72 n-C3H7. 75 C HgOzNzClS..- 41. 28 41. 51 3. 89 3. 95 12. 04 12.19 n-O4H 00 CvHuOzNgClS- 43.81 44.03 4. 49 4. 44 11.35 11.51 n-C H 78 CwHgOzNzCli. 46.06 45. 88 5. 02 5. 09 10. 74 10. 80 n-C H1 75 C11Hi5O2NzClS" 48. 07 48. 42 5. 5. 02 10. 10 10.13 n-C H15. 70 CnHnOzNzClS- 49. 90 50. 49 5.93 0. 09 9. 70 9. 43 n-CsH11 78 C1sHi0O2NzClS 51. 56 51.12 0. 32 6.01 0.25 0. 48 C H CH 68 CnHgOzN ClS 51. 34 51. 42 3.23 3.10 9. 97 10.08 0 11 83 C11II7OzN2ClS 49.53 49.87 2. 04 2. 49 10. 50 10.59

1 Yield is shown by weight percentage of the product relative to the starting material 3-ch1oro 6-mcrcaptopyridazine.

-65 C. under agitation for 2 hours, and then to the reaction mixture is added 150 parts by volume of water and the mixture is cooled with ice to separate out crystals. The crystals are collected by filtration and recrystallized with active carbon from ethanol-water to give 5 parts by weight of 3-chloro-6-thiocyanopyridazine, which melts at 123-124 C.

Analysis.-Calcd. for C H N SCl: C, 34.99; H, 1.17; N, 24.48. Found: C, 35.19; H, 1.28; N, 24.72.

(5) A mixture of 10 parts by weight of 3,6-dichioropyridazine, 16 parts by weight of sodium thiocyanate, and 100 parts by volume of 95% ethanol is warmed at 72-80 C. under agitation for 4 hours. Thereafter the same treatment as in (3) is applied to the reaction mixture to give 4 parts by Weight of 3-chlor0-6-thiocyanopyridazine.

(6) To a solution of 0.4 part by weight of sodium hydroxide and 1.9 parts by weight of 3-bromo-6-mercaptopyridazine in 10 parts by volume of water is added dropwise a solution of 1.1 parts by weight of cyanogen bromide in 5 parts by volume of ethanol under agitation and ice-cooling at 89 C. After further agitation for 10 minutes, the precipitated crystals are collected by filtration and recrystallized from acetone-water to give 1.9 parts by weight of 3-bromo-6-thiocyanopyridazine, which melts at 113-1 15 C. with decomposition.

Analysis.Calcd. for C H BrN S: N, 19.40. Found: N, 19.16.

(7) A mixture of 2.4 parts by weight of 3,6-dibromopyridazine, 2.3 parts by weight of ammonium thiocyanate, and 10 parts by volume of 95% ethanol is warmed on a water-bath at 70 C., whereupon a reaction takes place. After cooling, 40 parts by volume of water is added to the reaction mixture to separate out crystals, which are collected by filtration and recrystallized from acetonewater to give 1 part by weight of 3-bromo-6-thiocyanopyridazine, which melts at 110-115 C. with decomposition.

(8) To a solution of 0.3 part by weight of sodium hydroxide and 1 part by weight of 3-chloro-6-mercaptopyridazine in 10 parts by volume of water is added dropwise a. solution of 0.8 part by weight of ethyl chlorocarbonate in 2 parts by volume of acetone at room temperature under agitation. After further agitation for about 15 minutes, the precipitated crystals are collected by filtration and recrystallized from n-hexane to give 2.1 parts by weight of 3-chloro-6-cthoxycarbonylthiopyridazine, which melts at 49.5-50.5 C.

The above examples merely represent some preferred methods of preparing the active component of the antimicrobial compositions of this invention; however, compounds (I) produced through other methods are also applicable for the purpose of this invention. Other compounds whose preparation is not exemplified above are producible in analogous manner. In this specification, relationship between parts by weight and parts by volume is the same as that between grams and milliliters, and all percentages are in weight percentage, temperatures being all uncorrected.

The antimicrobial activity of compounds (I) is ilustrated only with reference to a typical presently-preferred representative thereof, namely 3-chloro-6-thiocyanopyridazine, in the following Table 3, which shows the minimum concentrations of 3-chloro-6-thiocyanopyridazine at which the growth of each microorganism in the table is completely inhibited. The standard agar dilution method was employed for determining the antimicrobial spectrum of 3-chloro-6-thiocyanopyridazine.

TABLE 3 Mini- Incumum inbation 'lcmp. hibitory Microorganism period C.) concen- (days) tration (mctn/ ml.)

(1) Saccharomycas cercvz'sz'ae 2 28 3.5 (2) Saccharomyces sake 2 28 2 (3) Zugasaccharcmyces soya 3 28 2 (4) Hansmula anomala. 2 28 2 (5) Torula TUbTtl 2 28 2 (6) Candida albicans. 2 37 5 (7) Candida tropicalis 2 37 7.5 (8) Candida pseudotropz'calis. 2 37 5 (9) Candida/:rusei 2 37 5 (10) Candida parakrusei 2 37 7.5 (11) Cryptocccms necformanx... 2 37 1 (12) Trichophytonintcrdigiiale. 2 37 1 (13) Trichophyton mentagrephyte 2 37 1 (14) Aspergillus nz'gcr 2 28 10 (15) Aspemillus oryzce 2 28 15 (16) Penicillium chrysogenum.-- 2 7 (17) Pmicillzum notatum 2 28 5 (18) Penicillz'umdinitutum 2 28 5 (19) Pemczllz'um citrmum 2 28 7.5 (20) Rhizopus wigricans 2 28 15 (21) lllucor mucsdofl 2 28 10 (22) Pirz'culcria oruza 2 28 7.5 (23) Gibberellafz/ ltttrot 2 28 2 (24) Hupochnus saaokii 3 28 2 (25) Helmintlmsporium sigmoidcum... 3 28 1 (26) Ophiotmlus mi abranus 2 28 5 (27) Gibberella saubinctii 2 28 2 (28) Pyrcnoplmra gramz'nao 2 28 1 (29) Ccphalosporium gramineum 2 28 2 TABLE 3-Continued adiuvant. The compositions may be ready-prepared ab initio or may e.g. be in the form of concentrates com- Mim prising a compound I as an active ingredient with ad- Q uvant, e.g. surface active agent, with only a minor bation Temp. hibitory Microorganism period C concert amount of the latter present. Such a concentrate is 232 economical as regards transportation, storage and the 13 like, and may easily be admixed-prior to use-with additional adjuvant to give the desIred eventual con- 30 Uslilago 2m 2 28 centration of active ingredient. It is suiiieient that an (31) Phytophthominf-stans... 2 28 1 (32) Macrospmum bgmtmzm 2 28 1 effective quantity 0? a compound I as an active agent be (32 Cemtostomglla flmbrmta 2 2g 1 applied to the plants or parts thereof to be protected or (34) Fusarium ozysporum f. m'veum" 2 28 3.5 i (35) Gommmchumlagmrium 2 28 20 treated, and that the ad uvant be selected on the basis 23s; lgusari-umoxyspgrumLlycopgrsi 2 2g of plant being treated, properties of active ingredient '57 homopsz's vermis 5 28 1 n (38) Rhizoctoma SCMLH" 5 28 and ad uvant, and the conditions of use.

gdimtimasdmmmm 5 2g Thus, if both the active agent and ad uvant(s) are 4 .0 rritis cinema 2 28 3.5 (41) Pythmmde, Bmmum" 2 28 2 water soluble, the composition may be applied in the g omerezia cmgul m 2 2g form of an aqueous spray. If, for example, a water-maeoisczriopsis vitis... 5 28 1 f (1L4) (iloeosporiumlaeticelar 3 28 1.5 soluble. adjuvant employed i h composlfion Gloe s o i'um Icril" 2 2s 2 comprises a water-insoluble antimicrobial ingredient-the g 20 composition may be applied as an aqueous dispersion. 2 2s 20 It is also possible, e.g. merely to mix the active agent, 2 2g 5 in owder form, with a owdered ad'uvant, and to use 5 2o 1 P 1 (5 a g 1 the mixture (dust) as such; or a mixture of pellets may Bacillus 6mm 1 be used. Or the powder mixture may be suspended in (5 g) Staphylo o cus mucus- 1 37 5 water or in an oil which, upon mixing with water, forms (50) SGTL7llZltltl;(1.. 1 37 1.5 1 (so id'z'crocnceusfla 1 37 5 e.g. an oil-lri-water emuision containing the active in- (57) Escherichia coli 1 37 5 i (58) Proteus vulgaris. 1 37 5 grcdlent' 5e Serratia marcesce i a 10 When the new compositions are used in dust form, the

'J o n u 1 32 n ad uvant (or diluent) may e.g. be talc, clay (such as fulwm s 1 7 1 28 lers earth, attapulgite, etc.), diatomaceous earth, lime, (63) Xaritho'nionas cifri' 1 28 3,5 (64) Emu-ma momma 1 28 10 calcium sulfate, kaolin and the like. When the compositions are used in the form of liquid, the adjuvant (dilu- The other compounds faning undar Compounds cut) is e.g. water, an aqueous solvent, a volatile or nonhave a similar antimicrobial activity against a wide variety Volatlle g Solvfint, an the Compound-as of microorganisms. aforeindicatedtaking the form of a solution, emulsion TABLE 4 Microorganism Compound 3-ch1oro-6-rnercaptopyridazine 100 20 10 35 10 35 35 Ei-bromo-ti-mercaptopyridazinm 100 50 50 35 100 75 50 5O 3-bromo- -thioeyanopyridnzinc 10 5 10 3.5 7.5 10 7.5 5 3-chloro-6-n1ethoxycarbonylthiopy 200 100 100 50 100 35 5O 35 3-chloro-6-etlioxycarbonylthiopyridazine 100 100 100 50 75 35. 50 35 3-cliloro-6-n-propoxycarhonylthiopyridazine. 200 50 l 50 100 50 50 50 3-cliloro-6-n-buty10xycnrbonylthiopyridazine, 500 350 100 50 200 50 100 75 B-chloro-G-n-amyloxycarbonylthiopyridazine 500 200 200 50 200 150 200 150 3-e1iloro-G-n-hexyloxycarbonylthiopyridazine. 500 100 100 50 100 50 50 50 3-ohloro0-n-l1eptyloxycarhonylthiopyridazine 500 50 100 50 100 50 50 75 B-ohloro-G-benzyoxycarbcnylthiopyridazine a 500 500 200 35 500 500 150 150 3-chloro-6-phcnoxyearbonylthiopyridazine 200 500 200 50 500 150 200 200 This is shown, by way of illustration, with respect to or suspension depending on the nature of the particular additional typical compounds of Formula I and reprematerials employed. sentative microorganisms in Table 4, setting forth the anti- The new antimicrobial compositions may contain surmierobial spectra of these compounds. The microface active agents such as wetting and dispersing agents organisms are identified by the numbers employed in and an emulsifier. They may also contain adherent or Table 3. Agar dilution method was also employed. sticking agents, and also other pesticides, fungicides, The figures represent the mlnimum inhibitory concentramanure or other fertilizer, growth controlling agents, etc., tion (meg/ml.) of the compounds. The result shown in all these additions being considered adjuvants. Ta l 4 s Obtained after y mcllbatmn 0f the In preparing an antimicrobially active aqueous suspenmicroorganisrns. sion, it is advantageous to include a surface active agent In Practlce, and for maximum efifictlveness, the anilin sufiicient amount to disperse and suspend a compound ul COmPOSItIOIJS P llwfintlon are P- I as the antimicrobial agent. Examples of such surface plied to the plants to be antimwroblally P' f active agents are the polyoxyethylene alkylarylethers, such be treated against Spread of mlcfoblal (1186356, 111 as Triton X-l00 (isooctyl phenol etherified with 10 to form of dust, emulsion, P aquegus 11 mols of ethylene oxide), as well as the other Tritons In other W0rd e ntimicro i l C0II1P0$1U0I1 0f the (higher molecular weight alkyl phenol polyglycol ethers, invention comprise essentially at least one active comdi i lk l h l l l l ethers, h hi h pound I and a suitable diluent (or extender and/ or conmolecular weight alkyl radical containing from 8 to 18 dimming agent) of the p COmmODlY fefeYffid 1 carbon atoms); also salts of the alkyl and al kylaryl sulconnection with the application of agricultural chemicals funni h as Du Pom MIR-189 d N l NR, a generally, as a pest control adjuvant. t is not intended, sodium salt; alkyl sulfates such as Dreft; alkylamide sulin this respect, that the present invention be limited to fonates, including fatty methyl taurides, such as Igepon any specific proportions of active ingredientfs) I and T; the fatty acid esters of polyhydric alcohols, such as Span; the ethylene oxide addition products of such esters, as for example Tween, a hexitol product; etc.

It is within the scope and ambit of the present invention to employ other adjuvants than those hereinbefore mentined-whether as solid diluents, liquid diluents, emulsifiers and/or dispersants, surface active agents or otherwise-those already mentioned being merely illustrative. The essence of the invention does not reside in any specific adjuvant but in a composition consisting essentially of at least one compound I and an appropriate and generally, but not necessarily, inert agricultural adjuvant, and in protecting plant life against fungus diseases or the spread of the latter, by applying to the plants or to portions thereof, such a composition in any suitable or appropriate manner (e.g. by dusting, spraying, etc.) and in an antimicrobially effective amount. The proportions of materials employed in the compositions may vary considerably, as has already been explained. Generally speaking, an antimicrobially effective amount is satisfied by the following quantitative relationships:

Dust compositions for direct application to vegetation may contain from 0.5 percent to 10% or more of the active ingredient(s) I. When the composition is designed as a concentrate for the preparation of sprays or more dilute dusts, the content of active ingredient(s) I may vary from about 10% to as high as 50%, the balance of the composition being one of the diluents and/ or surface active agents (adjuvants) previously enumerated. Liquid dispersions of the antimicrobial compositions in water may similarly vary from a very low percentage of active ingredient, e.g. 0.2 to 15%, where the dispersion is to be applied directly to the vegetation, to a relatively high percentage, e.g. 10 to 50%, where the dispersion is to be em ployed as a concentrate, the balance in each case being constituted by adjuvants.

Organic solvents, useful in compositions according to the invention, include for example non-phytotoxic solvents such as benzene, toluene, xylene and other petroleum distillate fractions or mixtures thereof, as well as the Carbitols and Cellosolves, etc.

Following are a number of examples of presently preferred embodiments of the invention.

Example 1 A mixture consisting of of 3-chloro-6-thiocyanopyridazine, 45% of acetone, and 50% of polyoxyethylene-nonylphenylether is diluted about 5 00-fold with water.

The resultant solution is effective in preventing the blast disease of rice plants when it is sprayed all over the leaves of the plant.

Example 2 The same mixture as in Example 1 is diluted IOO-fold with water.

In an application of the resultant solution for controlling anthracnose of cucumber, a marked efiect is observed in diminishing the occurrences of regions infected by the causal fungus Colletotricltum lagenarium Ell. et Halst., to about one-fifteenth in comparison with the control.

Example 3 The same solution as in Example 2 is sprayed over the leaves of rice plants. An effect of the treatment for controlling bacterial leaf blight of rice is clearly observed in appearing no more than one-tenth of regions, relative to the control, by the infection of the causal bacterium, XantlzOmonas oryzae (Uyeda and Ishiyarna) Dowson.

Example 4 The same mixture as in Example 1 is diluted 400-fold with water.

The solution so diluted is sprayed on pear trees with the purpose of protecting them from black spot. In the trees thus treated, the number of leaves suffering from Cir pear black spot caused by the infection of the fungus, Alternaria kikuclziana Tanaka, is one third relative to that observed in the untreated trees as the control.

Example 5 Leaves of pear trees which have regions suffering from black spot are sprayed with a solution of the same mixture as in Example 1 in 400-fold water. Seven days after the treatment, expansion of the area of the regions is inhibited to such an extent as less than one-sixth of that in the untreated leaves.

Example 6 A mixture consisting of 5% of 3-chloro-6-mercaptopyridazine, 30% of acetone, and of polyoxyethylenenony-lphenylether is diluted ZOO-fold with water.

The solution thus prepared is sprayed on leaves of pear trees sufiering from pear black spot to effectively suppress the expansion of area of the affected regions.

Example 7 A mixture consisting of 2% of 3-chloro-6-thiocyanopyridazine and 98% of talc is finely comminuted in a ball mill.

The mixture thus prepared may be applied to sweet potato to protect it from black rot disease.

Example 8 A mixture consisting of 20% of 3-chloro-6-mercaptopyridazine, of sodium dinaphthylmethane-disulphonate, and 10% of talc is powdered in the manner described in Example 7.

Example 9 A mixture consisting of 5% of 3-chloro-6-ethoxycarbonylthiopyridazine, 45% of acetone, and 50% of polyoxyethylene-nonylphenylether is diluted -fold with Water.

The solution thus prepared is sprayed on the leaves of cucumber plants. A remarkable effect in controlling anthracnose of cucumber is observed.

Example 10 A mixture consisting of 5% of 3-bromo-6-mercaptopyridazine, 35% of acetone, and 60% of polyoxyethylenenonylphenylether is diluted ZOO-fold with water.

The solution thus prepared is sprayed on leaves of pear trees which are suffering from black spot. It is observed, after seven days, that the treatment is useful to suppress the expansion of regions in the invaded leaves to 16.3% by area relative to that in the untreated leaves.

Example 12 A mixture consisting of 2% of 3-bromo-6-thiocyanopyridazine and 98% of tale is finely powdered in the manner described in Example 7.

Example 13 A mixture consisting of 20% of 3-bromo-6-mercaptopyridazine, 70% of disodium dinaphthylmethane-disulphonate, and 10% of tale is powdered in the manner described in Example 7.

The powdered product is useful as an antimicrobial concentrate dilutable with water, and the aqueous composition is effective in preventing rice blast.

Having thus disclosed the invention, what is claimed 1. An anti-microbial composition for agricultural use and, more especially, adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbial agent in the form of a compound of the formula wherein X is a halogen and R is a member selected from the group consisting of hydrogen, cyano and -COOR, wherein R' is a member selected from the group consisting of alkyl, benzyl and phenyl, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

2. An anti-microbial composition for agricultural use and, more especially adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbial agent in the form of 3-chloro- 6-thiocyano-pyridazine, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

3. An anti-microbial composition for agricultural use and, more especially adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbal agent in the form of 3-bromo- 6-thiocyano-pyridazine, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

4. An anti-microbial composition for agricultural use and, more especially adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbial agent in the form of 3- chloro-6-mercapto-pyridazine, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

5. An anti-microbial composition for agricultural use and, more especially adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbial agent in the form of 3-bromo-6-mercapto-pyridazine, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

6. An anti-microbial composition for agricultural use and, more especially adapted to protect a plant from diseases caused by fungi and by bacteria, which consists essentially of anti-microbial agent in the form of 3-c-hloro- 6-ethoxycarbonyl-thiopyridazine, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

7. A method of protecting a plant from diseases caused by fungi and by bacteria, which comprises applying to the plant an anti-microbially effective amount of an antimicrobial composition which consists essentially of an anti-microbial agent in the form of a compound of the formula Jim-SR N=N wherein X is a halogen and R is a member selected from the group consisting of hydrogen, cyano and -COOR', wherein R is a member selected from the group consisting of alkyl, benzyl and phenyl, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

8. A method of protecting a plant from diseases caused by Piricularia oryzae Cavara, which comprises applying to the plant a fungicidally effective amount of an antimicrobial composition which consists essentially of antimicrobial agent in the form of a compound of the forwherein X is a halogen and R is a member selected from the group consisting of hydrogen, cyano and -COOR', wherein R is a member selected from the group consisting of alkyl, benzyl and phenyl, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

10. A method of protecting a plant from diseases caused by Xanthomonas oryzae Dowson, which comprises applying to the plant a bactericidally effective amount of an anti-microbial composition which consists essentially of anti-microbial agent in the form of a compound of the formula wherein X is a halogen and R is a member selected from the group consisting of hydrogen, cyano and -C0O-R, wherein R is a member selected from the group consisting of alkyl, benzyl and phenyl, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

11. A method of protecting a plant from diseases caused by Alternaria kikuchiana Tanaka, which comprises applying to the plant a fungicidally effective amount of an anti-microbial composition which consists essentially of anti-microbial agent in the form of a compound of the formula rum-sit N=N wherein X is a halogen and R is a member selected from the group consisting of hydrogen, cyano and -COOR', wherein R is a member selected from the group consisting of alkyl, benzyl and phenyl, and an agricultural carrier therefor, said anti-microbial agent constituting from 0.2 to 50% of the composition.

References Cited in the file of this patent UNITED STATES PATENTS 2,764,584 Druey Sept. 25, 1956 2,835,626 Margot et al. May 20, 1958 2,858,311 Steck Oct. 28, 1958 2,861,917 Kosmin Nov. 25, 1958 2,863,802 Pyne Dec. 9, 1958 2,905,672 Steck Sept. 22, 1959 OTHER REFERENCES Helv. Chim. Acta, vol. 37, pages 121-l33, particularly page 126 (1954). 

1. AN ANTI-MICROBIAL COMPOSITION FOR AGRICULTURAL USE AND, MORE ESPECIALLY, ADAPTED TO PROTECT A PLANT FROM DISEASES CAUSED BY FUNGI AND BY BACTERIA, WHICH CONSISTS ESSENTIALLY OF ANTI-MICROBIAL AGENT IN THE FORM OF A COMPOUND OF THE FORMULA 